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I'm trying to get the most out of my dummy plug. Custom resolutions in nvidia are not showing up and the displayID method is not working. Wild guess is that it's seen as a dvi. I think dual link, maybe single. Reguardless DisplayID resolutions are not showing up so I must use regular restrictions (i think it's 600 something pixel clock)

I would like 3840x2160@90hz, but I cannot achieve 90hz. I would instead like the highest refresh rate possible. To achieve this I need the slowest scan out possible lol.

What is the minimum:
Horizontal front porch
Vertical front porch
Horizontal sync width
Vertical sync width
horizontal back porch/blanking/total
vertical back porch/blanking/total

ELK wrote: ↑

27 Jul 2020, 01:07

I'm trying to get the most out of my dummy plug. Custom resolutions in nvidia are not showing up and the displayID method is not working. Wild guess is that it's seen as a dvi. I think dual link, maybe single. Reguardless DisplayID resolutions are not showing up so I must use regular restrictions (i think it's 600 something pixel clock)

I would like 3840x2160@90hz, but I cannot achieve 90hz. I would instead like the highest refresh rate possible. To achieve this I need the slowest scan out possible lol.

What is the minimum:
Horizontal front porch
Vertical front porch
Horizontal sync width
Vertical sync width
horizontal back porch/blanking/total
vertical back porch/blanking/total

Minimums are display dependant, the firmware/scaler can have problems with too small numbers.

If the display firmware is not the limiting factor, then usually 8,8,8 for horizontals (24 pixel horizontal blanking) and 1,1,1 for verticals (3 pixel vertical blanking)

This would result in:
Horizontal Total = Horizontal Resolution + 24
Verticcal Total = Vertical Resolution + 3

The signal structure looks like this, taken from Custom Resolution Utility Glossary 101.

Minimum porches are actually zero, but AMD and NVIDIA both reject resolutions in the EDID with zero front porches, and DisplayID makes zero front porches impossible. Curiously, NVIDIA's custom resolutions will accept zero front porches.

Zero back porches are possible and accepted by both AMD and NVIDIA. CRU 1.3.1 and later will accept zero back porches.

Minimum sync width is one, because a zero sync width would mean no sync pulse.

AMD can't handle vertical blanking less than 5, and NVIDIA can't handle less than 3.

AMD will reject horizontal blanking less than 56 because it breaks their HDCP implementation, but the AMD/ATI Pixel Clock Patcher will remove that limit. I'm not aware of any such limitation with NVIDIA.